"use client";

import { useEffect, useRef, useState } from "react";
import Link from "next/link";
import { AnimatePresence, motion } from "framer-motion";
import { ArrowLeft, Send, StickyNote, Paperclip, X, MessageSquareText } from "lucide-react";
import { useTicketEvents } from "@/lib/events/use-ticket-events";
import { formatRelativeTime } from "@/lib/format";
import { Avatar } from "@/components/avatar";
import { AttachmentChip } from "@/components/attachment-chip";
import { TagPicker } from "./tag-picker";
import type { TicketDTO, MessageDTO, TicketStatus } from "@/lib/tickets/types";

const STATUS_LABEL: Record<TicketStatus, string> = {
  new: "Новая",
  open: "Открыта",
  pending: "В ожидании",
  closed: "Закрыта",
};

export function TicketThread({
  ticket: initialTicket,
  initialMessages,
  agents,
  currentUser,
}: {
  ticket: TicketDTO;
  initialMessages: MessageDTO[];
  agents: { id: string; name: string }[];
  currentUser: { id: string; role: "admin" | "agent" };
}) {
  const isAdmin = currentUser.role === "admin";
  const [ticket, setTicket] = useState(initialTicket);
  const [messages, setMessages] = useState(initialMessages);
  const [draft, setDraft] = useState("");
  const [visibility, setVisibility] = useState<"public" | "internal">("public");
  const [pendingFile, setPendingFile] = useState<File | null>(null);
  const [sending, setSending] = useState(false);
  const [cannedResponses, setCannedResponses] = useState<{ id: string; title: string; body: string }[]>([]);
  const [cannedOpen, setCannedOpen] = useState(false);
  const bottomRef = useRef<HTMLDivElement>(null);
  const fileInputRef = useRef<HTMLInputElement>(null);
  const cannedRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    fetch("/api/canned-responses")
      .then((res) => res.json())
      .then((data) => setCannedResponses(data.responses ?? []));
  }, []);

  useEffect(() => {
    function onClickOutside(e: MouseEvent) {
      if (cannedRef.current && !cannedRef.current.contains(e.target as Node)) setCannedOpen(false);
    }
    document.addEventListener("mousedown", onClickOutside);
    return () => document.removeEventListener("mousedown", onClickOutside);
  }, []);

  function insertCanned(body: string) {
    setDraft((prev) => (prev.trim() ? `${prev}\n${body}` : body));
    setCannedOpen(false);
  }

  useTicketEvents("/api/events", (event) => {
    if (event.type === "ticket.updated" && event.ticket.id === ticket.id) {
      setTicket(event.ticket);
    }
    if (event.type === "message.created" && event.ticketId === ticket.id) {
      // Internal notes are admin-only — an agent's SSE connection still
      // receives every event on the bus, so this has to be filtered here
      // too, not just at the initial server-rendered load.
      if (event.message.visibility === "internal" && !isAdmin) return;
      setMessages((prev) => (prev.some((m) => m.id === event.message.id) ? prev : [...prev, event.message]));
    }
  });

  useEffect(() => {
    bottomRef.current?.scrollIntoView({ behavior: "smooth" });
  }, [messages.length]);

  async function sendReply() {
    if (!draft.trim() && !pendingFile) return;
    setSending(true);

    let res: Response;
    if (pendingFile) {
      const formData = new FormData();
      formData.append("file", pendingFile);
      formData.append("caption", draft);
      formData.append("visibility", visibility);
      res = await fetch(`/api/tickets/${ticket.id}/attachments`, { method: "POST", body: formData });
    } else {
      res = await fetch(`/api/tickets/${ticket.id}/messages`, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ body: draft, visibility }),
      });
    }

    setSending(false);
    if (res.ok) {
      setDraft("");
      setPendingFile(null);
      if (fileInputRef.current) fileInputRef.current.value = "";
    }
  }

  async function updateStatus(status: TicketStatus) {
    const res = await fetch(`/api/tickets/${ticket.id}`, {
      method: "PATCH",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ status }),
    });
    if (res.ok) {
      const { ticket: updated } = await res.json();
      setTicket(updated);
    }
  }

  async function updateAssignee(assigneeId: string) {
    const res = await fetch(`/api/tickets/${ticket.id}`, {
      method: "PATCH",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ assigneeId: assigneeId || null }),
    });
    if (res.ok) {
      const { ticket: updated } = await res.json();
      setTicket(updated);
    }
  }

  return (
    <div className="flex h-[calc(100vh-11rem)] flex-col sm:h-[calc(100vh-6.5rem)]">
      <div className="mb-4 flex flex-wrap items-start justify-between gap-3">
        <div className="min-w-0">
          <Link href="/dashboard" className="mb-1 flex items-center gap-1 text-xs text-text-muted hover:text-text">
            <ArrowLeft size={13} />
            Дашборд
          </Link>
          <h1 className="truncate font-display text-lg font-bold">{ticket.subject}</h1>
          <span className="mb-2 flex items-center gap-1.5">
            <Avatar name={ticket.customerName} size={18} />
            <span className="text-sm text-text-muted">{ticket.customerName}</span>
          </span>
          <TagPicker
            ticketId={ticket.id}
            selectedTags={ticket.tags}
            onChange={(tags) => setTicket((t) => ({ ...t, tags }))}
          />
        </div>

        <div className="flex w-full shrink-0 items-center gap-2 sm:w-auto">
          <select
            value={ticket.status}
            onChange={(e) => updateStatus(e.target.value as TicketStatus)}
            className="min-w-0 flex-1 rounded-md border border-border bg-surface px-2 py-1.5 text-sm outline-none focus:border-accent sm:flex-none"
          >
            {Object.entries(STATUS_LABEL).map(([value, label]) => (
              <option key={value} value={value}>
                {label}
              </option>
            ))}
          </select>
          <select
            value={ticket.assigneeId ?? ""}
            onChange={(e) => updateAssignee(e.target.value)}
            className="min-w-0 flex-1 rounded-md border border-border bg-surface px-2 py-1.5 text-sm outline-none focus:border-accent sm:flex-none"
          >
            <option value="">Не назначено</option>
            {agents.map((agent) => (
              <option key={agent.id} value={agent.id}>
                {agent.name}
              </option>
            ))}
          </select>
        </div>
      </div>

      <div className="card flex-1 overflow-y-auto p-4">
        <AnimatePresence initial={false}>
          {messages.map((message) => (
            <MessageBubble key={message.id} message={message} />
          ))}
        </AnimatePresence>
        <div ref={bottomRef} />
      </div>

      <div className="mt-3">
        {/* Internal notes are admin-only — agents only ever reply to the client, so there's nothing to toggle. */}
        {isAdmin && (
          <div className="mb-1.5 flex gap-1">
            <button
              type="button"
              onClick={() => setVisibility("public")}
              className={`rounded-full px-2.5 py-1 text-xs font-medium transition-colors ${
                visibility === "public" ? "bg-accent-soft text-accent-soft-text" : "text-text-faint hover:text-text-muted"
              }`}
            >
              Ответ клиенту
            </button>
            <button
              type="button"
              onClick={() => setVisibility("internal")}
              className={`rounded-full px-2.5 py-1 text-xs font-medium transition-colors ${
                visibility === "internal" ? "bg-warning-soft text-warning-soft-text" : "text-text-faint hover:text-text-muted"
              }`}
            >
              Заметка для команды
            </button>
          </div>
        )}
        {pendingFile && (
          <div className="mb-1.5 flex items-center gap-2 rounded-md border border-border bg-surface-hover px-2.5 py-1.5 text-xs">
            <Paperclip size={12} />
            <span className="flex-1 truncate">{pendingFile.name}</span>
            <button type="button" onClick={() => setPendingFile(null)} className="text-text-muted hover:text-text">
              <X size={13} />
            </button>
          </div>
        )}
        <div className="flex gap-2">
          <input
            ref={fileInputRef}
            type="file"
            className="hidden"
            onChange={(e) => setPendingFile(e.target.files?.[0] ?? null)}
          />
          <textarea
            value={draft}
            onChange={(e) => setDraft(e.target.value)}
            onKeyDown={(e) => {
              if (e.key === "Enter" && !e.shiftKey) {
                e.preventDefault();
                sendReply();
              }
            }}
            rows={2}
            placeholder={visibility === "internal" ? "Заметка — клиент её не увидит…" : "Ответить клиенту…"}
            className={`flex-1 resize-none rounded-md border px-3 py-2 text-sm outline-none ${
              visibility === "internal"
                ? "border-warning-soft-text/30 bg-warning-soft focus:border-warning"
                : "border-border bg-surface focus:border-accent"
            }`}
          />
          <div ref={cannedRef} className="relative self-end">
            <button
              type="button"
              onClick={() => setCannedOpen((v) => !v)}
              className="btn btn-ghost"
              title="Шаблоны ответов"
            >
              <MessageSquareText size={15} />
            </button>
            {cannedOpen && (
              <div className="card absolute bottom-full right-0 z-20 mb-2 max-h-64 w-72 overflow-y-auto p-1">
                {cannedResponses.length === 0 && (
                  <p className="p-2 text-xs text-text-faint">Шаблонов пока нет</p>
                )}
                {cannedResponses.map((c) => (
                  <button
                    key={c.id}
                    type="button"
                    onClick={() => insertCanned(c.body)}
                    className="block w-full rounded-md px-3 py-2 text-left text-sm hover:bg-surface-hover"
                  >
                    <p className="font-medium">{c.title}</p>
                    <p className="truncate text-xs text-text-faint">{c.body}</p>
                  </button>
                ))}
              </div>
            )}
          </div>
          <button
            type="button"
            onClick={() => fileInputRef.current?.click()}
            className="btn btn-ghost self-end"
            title="Прикрепить файл"
          >
            <Paperclip size={15} />
          </button>
          <button
            onClick={sendReply}
            disabled={sending || (!draft.trim() && !pendingFile)}
            className={visibility === "internal" ? "btn self-end bg-warning text-white hover:brightness-95" : "btn btn-primary self-end"}
          >
            {visibility === "internal" ? <StickyNote size={15} /> : <Send size={15} />}
          </button>
        </div>
      </div>
    </div>
  );
}

function MessageBubble({ message }: { message: MessageDTO }) {
  const isAgent = message.authorType === "agent";
  const isSystem = message.authorType === "system";

  if (isSystem) {
    return (
      <p className="my-2 text-center text-xs text-text-faint">{message.body}</p>
    );
  }

  if (message.visibility === "internal") {
    return (
      <motion.div
        layout
        initial={{ opacity: 0, y: 8 }}
        animate={{ opacity: 1, y: 0 }}
        transition={{ duration: 0.18 }}
        className="mb-3 rounded-lg border border-dashed border-warning-soft-text/40 bg-warning-soft px-3 py-2"
      >
        <p className="mb-1 flex items-center gap-1.5 text-[11px] font-semibold text-warning-soft-text">
          <StickyNote size={11} />
          Внутренняя заметка
        </p>
        <p className="mb-1 whitespace-pre-wrap text-sm">{message.body}</p>
        {message.attachments.map((a) => (
          <AttachmentChip key={a.id} attachment={a} />
        ))}
        <p className="text-[11px] text-warning-soft-text/80">
          {message.authorName} · {formatRelativeTime(message.createdAt)}
        </p>
      </motion.div>
    );
  }

  return (
    <motion.div
      layout
      initial={{ opacity: 0, y: 8 }}
      animate={{ opacity: 1, y: 0 }}
      transition={{ duration: 0.18 }}
      className={`mb-3 flex ${isAgent ? "justify-end" : "justify-start"}`}
    >
      <div className={`max-w-[75%] rounded-lg px-3 py-2 text-sm ${isAgent ? "bg-accent text-white" : "bg-surface-hover"}`}>
        <p className="mb-1 whitespace-pre-wrap">{message.body}</p>
        {message.attachments.map((a) => (
          <AttachmentChip key={a.id} attachment={a} />
        ))}
        <p className={`text-[11px] ${isAgent ? "text-white/70" : "text-text-faint"}`}>
          {message.authorName} · {formatRelativeTime(message.createdAt)}
        </p>
      </div>
    </motion.div>
  );
}